1. Field of the Invention
The present invention relates to a paper sheet counting machine for counting the number of paper sheet such as paper currency.
2. Description of the Prior Art
There is known in the prior art a paper currency counting machine in which the sheets of paper currency are sucked and turned over one by one by the vacuum prevailing in suction tubes arranged so rotatably in a rotary cylinder as to revolve on their axes and around the axis of the rotary cylinder in accordance with the rotations of the rotary cylinder so that the number of the paper sheets may be counted in terms of the output signal of a sensor made detective of the passage of the suction tubes. The present Applicant has already made proposals such as Japanese Patent Application No. 57-70859, 56-201380 or 56-196448. Now, these proposals have such advantages and subject matters to be aimed at as will be described in the following. In the Japanese Patent Application No. 57-70859, specifically, suction tubes are located by means of both operation members (iron members, for example) arranged on the outer circumference of a rotary cylinder in a manner to correspond to the suction tubes and a sensor for detecting the operation members so that one suction tube may be stopped at a stand-by position (in which it substantially faces the paper sheets to be counted). As is different from the prior art method by which the stop is mechanically effected, therefore, the suction tube can be stopped with neither fail nor chattering at the stand-by position. Despite of this advantage, however, there are left as the subject matters the points that a long time elapses before the paper sheets are sucked and that the counting operations are not started, in case the paper sheets are unabled to be sucked by the suction tube as a result of disturbances of the paper sheets, so that a vacuum pump is left continuously rotating.
Next, in the Japanese Patent Application No. 56-201380, in order to eliminate the aforementioned disadvantages, the suction tube is set in advance prior to the start of the counting operations not in the stand-by position but in a start position, in which the suction tube has its inside blocked and sealed from the outside, and a vacuum pump is driven so that the counting operations are started when the vacuum pressure prevailing in the suction tube reaches a predetermined level. As a result, the start of the counting operations is ensured, but the paper sheets are liable to be folded between the suction tubes in some cases in which a mistake in the counting operations may take place. In order to obviate this mistake, therefore, there arises a disadvantage that a regulating member for firmly holding the paper sheets in position on the holder is made indispensable to complicate the overall construction.
In the Japanese Patent Application No. 56-196448, on the other hand, the holder charged up with the paper sheets is swung from a charge position (or an open position) to a count position (or a closed position), and the suction tubes are inversely revolved around a rotary cylinder carrying the suction tubes by inversely rotating the rotary cylinder so that the paper sheets can be prevented from being folded between the suction tubes. Depending upon the positions of the suction tubes when the holder is set in the closed position, however, the holder exerts a strong thrust upon the suction tube during the aforementioned inverse rotation so that the counter motor is brought into an overload state to invite a disadvantage that the motor has its performance deteriorated. In order that just after completeness of reverse revolution of the suction tubes the suction tube may be forwardly revolved for its sucking and turning over operations, moreover, a conduit for providing communication between the suction tube and a vacuum pump is blocked and sealed from the outside by the action of a solenoid valve to raise the vacuum pressure in the aforementioned conduit in advance thereby to make it necessary to increase the suction of the suction tube. This necessity invites a disadvantage that the construction is also complicated.